1. Field of the Invention
The present invention relates to an encoding quantity control method and video signal encoding apparatus for spatial scalability profile which is hierarchical coding in a spatial axis direction standardized (ISO/IEC 13818-2) by the ISO Moving Picture Experts Group (MPEG), or for other hierarchical coding techniques, and also relates to the storing and decoding of video signals compressed by the MPEG standard.
2. Description of the Prior Art
Conventional video signal layering-encoding apparatus is based on the spatial scalability profile which is hierarchical coding in a spatial axis direction standardized (ISO/IEC 13818-2) by the ISO Moving Picture Experts Group (MPEG).
The constitution and operation of the conventional video signal layering-encoding apparatus will hereinafter be described in reference to FIG. 22, which is a block diagram of the conventional video signal layering-encoding apparatus.
As shown in FIG. 22, an input video signal 5000 is converted to a lower resolution video signal than the input video signal 5000 by a resolution converter 5001.
A motion detector 5002 stores the output of the resolution converter 5001 (the encoded frame of the input video signal 5000) in image memory 5003 and also detects the motion of a macroblock unit from the encoded frame and the previously encoded and decoded past reference frame in the image memory 5003. A motion compensator 5004 outputs a differential signal between the video signal of the encoded frame and the reproduced video signal of the reference frame detected by the motion detector 5002 in the unit of a macroblock. A discrete cosine transform (DCT) unit 5005 outputs the output (differential signal) of the motion compensator 5004 as DCT coefficients for each block. A quantizer 5006 quantizes the DCT coefficients by a quantization step (i.e., a divisor employed in quantization) specified by an encoding rate controlled 5007 and then outputs the quantized DCT coefficients. An inverse quantizer 5008 inversely quantizes the DCT coefficients quantized at the quantizer 5006 by the quantized quantization step and then outputs the inversely quantized DCT coefficients. An inverse DCT (IDCT) unit 5009 outputs the output of the inverse quantizer 5008 as inverse DCT coefficients. A motion compensator 5010 generates a reproduced video signal by adding the output of the IDCT unit 5009 and the video signal of the reference frame whose motion was compensated at the motion compensator 5004, and then stores the reproduced video signal in the image memory 5003. A variable-length encoder 5011 variable-length encodes the output of the quantizer 5006 and a predetermined flag and then outputs the variable-length encoded video signal. A buffer 5012 stores the variable-length encoded video signal temporarily and adjusts the output speed of output data thereof. That is, the buffer 5012 outputs a variable-length encoded video signal with low resolution.
The encoding rate controller 5007 determines the quantization step of the encoded frame for each macroblock, based on the output (differential signal) of the motion compensator 5004, the encoded length of the encoded video signal, and the residual quantity information on the buffer 5012.
On the other hand, the resolution converter 5013 resolution converts the output (reproduced video signal) of the motion compensator 5010, i.e., converts the resolution of the reproduced video signal to the same resolution as the input video signal 5000 and then stores it in image memory 5015. A motion detector 5014 stores the encoded frame of the input video signal 5000 in the image memory 5015 and also detects the motion of a macroblock unit from the encoded frame, the previously encoded and decoded past reference frame (high resolution video signal) in the image memory 5015, and from the reference frame that is the video signal of the same time among the low resolution signals which are the outputs of the resolution converter 5013. That is, in this motion detection, the motion detector 5014 compares the encoded frame of the input video signal 5000 with the above-mentioned past reference frame, the above-mentioned reference frame of the same time, and a reference frame generated by a combination of these, and then detects a reference frame with the highest correlation in the unit of a macroblock. The reference frame with the highest correlation is output from the image memory 5015 to the motion compensator 5016.
The motion compensator 5016 outputs a differential signal between the video signal of the encoded frame and the reproduced video signal of the reference frame detected by the motion detector 5014 in the unit of a macroblock. A DCT unit 5017 outputs the output (differential signal) of the motion compensator 5016 as DCT coefficients for each block. A quantizer 5018 quantizes the DCT coefficients by a quantization step specified by an encoding rate controller 5019 and then outputs the quantized DCT coefficients. An inverse quantizer 5020 inversely quantizes the DCT coefficients quantized at the quantizer 5018 by the quantized quantization step and then outputs the inversely quantized DCT coefficients. An IDCT unit 5012 outputs the output of the inverse quantizer 5020 as inverse DCT coefficients. A motion compensator 5022 generates a reproduced video signal by adding the output of the IDCT unit 5021 and the reproduced video signal of the reference frame whose motion was compensated at the motion compensator 5016, and then stores the reproduced video signal in the image memory 5015. A variable-length encoder 5023 variable-length encodes the output of the quantizer 5018 and a predetermined flag and then outputs the variable-length encoded video signal. A buffer 5024 stores the variable-length encoded video signal temporarily and adjusts the output speed of output data thereof. That is, the buffer 5024 outputs a variable-length encoded video signal with high resolution.
The encoding rate controller 5019 determines the quantization step of the encoded frame for each macroblock, based on the outputs (differential signal) of the motion compensator 5016, the encoded length of the encoded video signal, and the residual quantity of the buffer 5024.
In such a conventional video signal layering-encoding system, however, the two encoding rate controllers 5007 and 5019 control the encoding quantities individually and independently so that the mean bit rates of the outputs become constant, respectively. For that reason, in both the cases where the input video signal 5000 contains and does not almost contain a large quantity of high frequency component, the encoding quantities are controlled in the same manner. More specifically, the control for the encoding quantity between layers is not entirely performed according to the input video signal 5000.
In addition, although encoding efficiency has been improved in encoding a high resolution video signal by an increase in the number of reference images for motion vector detection, an improvement in the encoding efficiency by using a low resolution signal more effectively has not been performed.
Next, a conventional digital broadcast decoding apparatus will be described in reference to FIG. 23, which illustrates a block diagram of the conventional digital broadcast decoding apparatus.
The conventional digital broadcast decoding apparatus shown in FIG. 23 is a receiver for a digital broadcast that employs video and audio signals compressed and encoded by the MPEG standard.
As shown in FIG. 23, a demodulating section 6001 performs a predetermined demodulation on a received digital broadcast 6000, thereby generating an MPEG stream. A separating section 6002 separates video and audio signal compressed streams on a predetermined channel from the generated MPEG stream. An audio signal decoding section 6003 decodes the audio signal compressed stream and outputs an audio signal 6020.
In a video signal decoding section 6004, (1) a variable-length decoder 6005 variable-length decodes the aforementioned video signal compressed stream and then outputs the motion vector of a macroblock unit, a quantization step (i.e., a divisor employed in quantization), and DCT coefficients, (2) an inverse quantizer 6006 inversely quantizes the DCT coefficients by the quantization step decoded in the unit of a macroblock, (3) an IDCT unit 6007 outputs the inversely quantized DCT coefficients as IDCT coefficients, (4) a motion compensator 6008 reproduces a video signal from the IDCT coefficients obtained by employing a motion vector in a macroblock unit and also from a signal stored in memory 6004, and (5) a memory controller 6010 controls the storage of the reproduced video signal in the memory 6004, the output of the video signal stored in the memory 6004 to the motion compensator 6008, and the output of the reproduced video signal, thereby outputting a decoded video signal 6021.
Such a conventional digital broadcast decoding system reproduces only a video signal present on one channel and, therefore, has the disadvantage that a broadcasting program on a different channel cannot be monitored on a small screen within a main screen at the same time. To achieve this, the system can be equipped with a plurality of devices of the same structure. But in such a case, there is a disadvantage that the cost is significantly increased.
Next, a conventional digital broadcasting signal storage will be described in reference to FIG. 24, which illustrates a block diagram of the conventional digital broadcasting signal storage.
The conventional digital broadcast storage shown in FIG. 24 is a video tape recorder (e.g., D-VHS) for recording a digital broadcast which employs video and audio signals compressed and encoded by the MPEG standard.
As shown in FIG. 24, a demodulating section 7001 performs a predetermined demodulation on a received digital broadcast, thereby generating an MPEG stream. A separating section 7002 separates a transport stream (TS) on a predetermined channel from the MPEG stream. A storing section 7003 stores the separated TS in a storage medium 7004.
In such a conventional digital broadcasting signal storage, storage media are restrained either by a large quantity of data to be stored or due to the fast storing speed of requisite data. Furthermore, since different video signals in various formats (resolution, frame frequency, etc.) are present in storage media, there is a problem that video signals are difficult to handle.
It is an object of the present invention to provide a video signal layering-encoding system and a video signal layering-encoding method which are capable of controlling the quantity of encoding between layers in accordance with an input video signal.
Another object of the invention is to provide a digital broadcast decoding system, a digital broadcast decoding method, and a video signal decoding system which are capable of monitoring a plurality of broadcasting programs (including a broadcasting program on a different channel) by simpler constitution than prior art.
Still another object of the invention is to provide a digital broadcasting signal storage and a digital broadcasting signal storing method which are capable of solving, for example, the aforementioned problems that storage media are restrained either by a large quantity of data to be stored or due to the fast storing speed of requisite data and that since different video signals in various formats (resolution, frame frequency, etc.) are present in storage media, video signals are difficult to handle.
The first invention of the present invention is a method of layering and encoding an input video signal on the basis of spatial resolution, comprising:
a first resolution tranformation step of generating a second video signal with low resolution from a first video signal with high resolution which is said input video signal;
a first encoding step of encoding said second video signal;
a decoding step of decoding the encoded second video signal;
a second resolution transformation step of generating a third video signal with the same high resolution as said first video signal, based on the decoded video signal obtained by decoding said second video signal;
a second encoding step of encoding a video signal with the same high resolution as said first video signal, obtained based on said first video signal and said third video signal;
a high frequency component information output step of outputting information on a high frequency component which is included in said first video signal or said second video signal; and
an encoding quantity control step of controlling an encoding rate at which said second video signal is encoded by said first encoding step and an encoding rate at which said first video signal is encoded by said second encoding step, based on the output high frequency component information.
The second invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
second encoding means to encode said first video signal, based on a time axis correlation of the first video signal and based on said third video signal as a predicted video signal;
frequency distribution measuring mean to measure a frequency distribution of said first video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said first video signal is encoded by said second encoding means, based on the measured frequency distribution.
With this, for example, by having a frequency distribution judgment unit, encoding quantity control according to a frequency component contained in an input video signal can be performed between layers.
The third invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
differential signal generating means to generate a fourth video signal which is a differential signal between said first video signal and said third video signal;
motion detection means to detect motion from said first video signal;
second encoding means to encode said fourth video signal, based on the detected motion of said firs video signal;
frequency distribution measuring means to measure a frequency distribution of said first video signal; and
encoding quantity control mean to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said fourth video signal is encoded by said second encoding means, based on the measured frequency distribution.
With this, for example, by having a frequency distribution judgment unit, encoding quantity control according to a frequency component contained in an input video signal can be performed between layers in the hierarchical coding in which an encoded signal at a high resolution component is a differential signal with a video signal reproduced from a low resolution component.
The fourth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
motion detection means to detect motion from said second video signal;
second encoding means to encode said first video signal, based on a time axis correlation of the first video signal and based on said third video signal as a predicted video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said first video signal is encoded by said second encoding means, based on the detected motion of said second video signal.
The fifth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
motion detection means to detect motion from said first video signal;
second encoding means to encode said first video signal, based on a time axis correlation of the first video signal and based on said third video signal as a predicted video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding jeans and an encoding rate at which said first video signal is encoded by said second encoding means, based on the detected motion of said first video signal.
With this, for example, by having a motion judgment unit, encoding quantity control according to the motion of an input video signal can be performed between layers.
The sixth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
differential signal generating means to generate a fourth video signal which is a differential signal between said first video signal and said third video signal;
motion detection means to detect motion from said first video signal;
second encoding means to encode said fourth video signal, based on the detected motion of said first video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said fourth video signal is encoded by said second encoding means, based on the detected motion of said first video signal.
With this, for example, by having a motion judgment unit, encoding quantity control according to the motion of an input video signal can be performed between layers in the hierarchical coding in which an encoded signal at a high resolution component is a differential signal with a video signal reproduced from a low resolution component.
The seventh invention of eh present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
motion detection means to detect motion from said second video signal;
second encoding means to encode said first video signal, based on a time axis correlation of the first video signal and based on said third video signal as a predicted video signal;
frequency distribution measuring means to measure a frequency distribution of said first video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said first video signal is encoded by said second encoding means, based on the detected frequency distribution and the detected motion of said second video signal.
The eighth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
motion detection means to detect motion from said first video signal;
second encoding means to encode said first video signal, based on a time axis correlation of the first video signal and based on said third video signal as a predicted video signal;
frequency distribution measuring means to measure a frequency distribution of said first video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said first video signal is encoded by said second encoding means, based on the detected frequency distribution and the detected motion of said first video signal.
With this, for example, by having a frequency distribution judgment unit, encoding quantity control according to a frequency component contained in an input video signal can be performed between layers, and by having a motion judgment unit, encoding quantity control according to the motion of an input video signal can be performed between layers.
The ninth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
differential signal generating means to generate a fourth video signal which is a differential signal between said first video signal and said third video signal;
motion detection means to detect motion from said first video signal;
second encoding means to encode said fourth video signal, based on the detected motion of said first video signal;
frequency distribution measuring means to measure a frequency distribution of said first video signal; and
encoding quantity control means to control an encoding rate at which said second video signal is encoded by said first encoding means and an encoding rate at which said fourth video signal is encoded by said second encoding means, based on the measured frequency distribution and the detected motion of said first video signal.
With this, for example, by having a frequency distribution judgment unit, encoding quantity control according to a frequency component contained in an input video signal can be performed between layers in the hierarchical coding in which an encoded signal at a high resolution component is a differential signal with a video signal reproduced from a low resolution component, and by having a motion judgment unit, encoding quantity control according to the motion of an input video signal can be performed between layers in the hierarchical coding in which an encoded signal at a high resolution component is a differential signal with a video signal reproduced from a low resolution component.
The seventeenth invention of the present invention is a method of layering and encoding an input video signal on the basis of spatial resolution, comprising:
a first resolution transformation step of generating a second video signal with low resolution from a first video signal with high resolution which is said input video signal;
a first encoding step of encoding said second video signal;
a decoding step of decoding the encoded second video signal;
a second resolution transformation step of generating a third video signal with the same high resolution as said first video signal, based on the decoded video signal obtained by decoding said second video signal; and
a second encoding step of encoding said first video signal, based on a plurality of encode modes;
wherein, when in said second encoding step said encoding is performed by employing an encode mode based on bidirectional prediction in a time axis direction among said plurality of encode modes, only information indicating which of said first video signal or said decoded video signal is utilized by the encoding in said first encoding step or encoding in said second encoding step is encoded.
The eighteenth invention of the prevent invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal; and
second encoding means to encode each frame of said first video signal by at least one of the encode modes among (1) spatial inter-resolution predictive coding which employs prediction in a spatial axis direction employing said third video signal, (2) intraframe coding which employs only data within said frame, (3) interframe forward predictive coding which employs forward prediction in a time axis direction, and (4) interframe bidirectional predictive coding which employs bidirectional prediction in the time axis direction;
wherein, when said interframe bidirectional predictive coding is performed by said second encoding means, only a motion vector obtained by interframe bidirectional prediction is encoded.
With this, for example, by encoding only a motion vector based on bidirectional prediction between frames, a reduction in the quantity of encoding becomes possible, so the encoding efficiency of high resolution signals can be enhanced.
The nineteenth invention of eh present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode each frame of said second video signal by either (1) intraframe coding which employs only data within said frame, (2) interframe forward predictive coding which employs forward prediction in a time axis direction, or (3) interframe bidirectional predictive coding which employs bidirectional prediction in the time axis direction;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal; and
second encoding means to encode each frame of said first video signal by at least one of the encode modes among (1) spatial inter-resolution predictive coding which employs prediction in a spatial axis direction employing said third video signal, (2) intraframe coding which employs only data within said frame, (3) interframe forward predictive coding which employs forward prediction in a time axis direction, and (4) interframe bidirectional predictive coding which employs bidirectional prediction in the time axis direction;
wherein, when said interframe bidirectional predictive coding is performed by said second encoding mean, only a motion vector obtained by interframe bidirectional prediction is encoded.
With this, for example, in addition to the aforementioned advantages, the encoded type of each frame becomes the same in encoding a low resolution signal and a high resolution signal, so it becomes possible to apply the motion vector of a low resolution signal when a high resolution signal is decoded, and consequently, error tolerance is increased.
The twenty-fifth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
a second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal; and
second encoding means to encode each frame of said first video signal by at lest one of the encode modes among (1) spatial inter-resolution predictive coding which employs prediction in a spatial axis direction employing said third video signal, (2) intraframe coding which employs only data within said frame, (3) interframe forward predictive coding which employs forward prediction in a time axis direction, and (4) interframe bidirectional predictive coding which employs bidirectional prediction in the time axis direction;
wherein said second encoding means encodes frames of said first video signal at intervals of a predetermined number of frames by said spatial inter-resolution predictive coding alone.
With this, for example, intraframe coding is not performed on high resolution signals, so a reduction in the quantity of encoding becomes possible, so that the encoding efficiency of high resolution signals can be enhanced.
The twenty-sixth invention of the present invention is an apparatus for layering and encoding a video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is an input video signal;
first encoding means to encode said second video signal;
decoding means to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same resolution as said first video signal from the decoded video signal of said second video signal;
second encoding means to encode each frame of said first video signal by at least one of the encode modes among (1) spatial inter-resolution predictive coding which employs prediction in a spatial axis direction employing said third video signal, (2) intraframe coding which employs only data within said frame, (3) interframe forward predictive coding which employs forward prediction in a time axis direction, and (4) interframe bidirectional predictive coding which employs bidirectional prediction in the time axis direction; and
motion vector detection means to detect a motion vector between frames of said first video signal;
wherein said second encoding means performs encoding by employing the motion vector detected by said motion vector detection means, and said first encoding means performs encoding by employing a motion vector obtained by multiplying the motion vector detected at said motion vector detection means by a predetermined number.
With this, for example, as the motion vector detection of the frame of a high resolution signal is not performed, overall circuit size can be reduced, and as the motion vector is not encoded, the encoding efficiency of high resolution signals can be enhanced.
The twenty-eight invention of the present invention is a method of layering and encoding an input video signal on the basis of spatial resolution, comprising:
a first resolution transformation step of generating a second video signal with low resolution from a first video signal with high resolution which is said input video signal;
a first encoding step of encoding said second video signal;
a decoding step of decoding the encoded second video signal;
a second resolution transformation step of generating a third video signal with the same high resolution as said first video signal, based on the decoded video signal obtained by decoding said second video signal;
a differential signal generation step of computing a data difference between frames of said first and third video signals which correspond with each other and generating a differential signal;
a band dividing step of dividing the generated differential signal into a plurality of predetermined bands and generating a band dividing signal; and
a second encoding step of encoding the generated band dividing signal.
The twenty-ninth of the present invention is an apparatus for layering and encoding an input video signal on the basis of spatial resolution, comprising:
first resolution transformation means to generate a second video signal with low resolution from a first video signal with high resolution which is said input video signal;
first encoding means to encode said second video signal;
decoding mean to decode the encoded second video signal;
second resolution transformation means to generate a third video signal with the same high resolution as said first video signal, based on the decoded video signal obtained by decoding said second video signal;
differential signal generation means to compute a data difference between frames of said first and third video signals which correspond with each other and generate a differential signal;
band dividing means to divide the generated differential signal by said differential signal generation means into a plurality of predetermined bands and generate a band dividing signal; and
second encoding means to encode said band dividing signal generated by said band dividing means.
With this, for example, different encoding methods are employed in a low resolution signal and a high resolution signal, so if both signals are combined together, a high resolution signal can be encoded so that it is effective and therefore the picture quality of a high resolution signal can be improved.
The thirtieth invention of the present invention is a digital broadcast decoding method of decoding a broadcasting signal compressed by the Moving Picture Experts Group (MPEG) standard and multiplexed, comprising:
a demodulation step of performing a predetermined demodulation on said broadcasting signal;
a separation step of separating the demodulated broadcasting signal into a video signal compressed stream and an audio signal compressed stream on a first channel;
a first video signal decoding step of decoding the separated video signal compressed stream present on said first channel;
a first audio signal decoding step of decoding the separated audio signal compressed stream present on said first channel; and
a second video signal decoding step of decoding a video signal compressed stream present on a second channel different from said first channel;
wherein in said second video signal decoding step, (1) the video signal compressed stream on said second channel is decoded, (2) a motion vector, and a DC component in DCT coefficients are extracted, or a DC component and some of DCT coefficients excluding the DC component are extracted, and (3) based on the extracted contents, said second video signal is decoded.
The thirty-first invention of the present invention is a digital broadcast decoding apparatus for decoding a broadcasting signal which is generated from a video signal and an audio signal which are compressed by the Moving Picture Experts Group (MPEG) standard, multiplexed and modulated, comprising:
a demodulating section to perform a predetermined demodulation on said digital broadcasting signal;
a separating section to separate the demodulated broadcasting signal into a video signal compressed stream and an audio signal compressed stream on at least one channel by releasing said multiplexing;
a first video signal decoding section to decode the separated video signal compressed stream present on a predetermined channel;
an audio signal decoding section to decode the separated audio signal compressed stream present on said predetermined channel;
a second video signal decoding section to decode a video signal compressed stream present on a channel other than said predetermined channel and to output the decoded signal; and
a video signal overlaying section to overlay a video signal output of said second video signal decoding section at a predetermined position on a video signal output of said first video signal decoding section and to output the overlaid signal;
wherein said second video signal decoding section has:
a variable-length decoder which (1) variable-length decodes said video signal compressed stream, (2) extracts a motion vector and a DC component, or (3) extracts a quantization step when said DC component is quantized, the quantization step being a divisor employed in the quantization;
inverse differential pulse code modulation (DPCM) unit to perform inverse DPCM only when DPCM has been performed on said DC component;
an inverse quantizer to perform inverse quantization only when said DC component has been quantized;
memory to store the decoded video signal;
a motion compensator to compensate motion by employing both a video signal compensated and decoded after said motion vector has been transformed by a predetermined transformation and a video signal stored in said memory; and
a memory controller to control writing of data to said memory and reading of data from said memory.
With this, for example, a broadcasting program on a different channel can be readily displayed on a small screen within a main screen when a digital broadcast is received.
The thirty-third invention of the present invention is a digital broadcast decoding apparatus for decoding a broadcasting siganal which is generated from a video signal and an audio signal which are compressed by the Moving Picture Experts Group (MPEG) standard, multiplexed and modulated, comprising:
a demodulating section to perform a predetermined demodulation on said digital broadcasting signal;
a separating section to separate the demodulated broadcasting signal into a video signal compressed stream and an audio signal compressed stream on at least one channel by releasing said multiplexing;
a first video signal decoding section to decode the separated video signal compressed stream present on a predetermined channel;
an audio signal decoding section to decode the separated audio signal compressed stream present on said predetermined channel;
a second video signal decoding section to decode a video signal compressed stream present on a channel other than said predetermined channel and to output the decoded signal; and
a video signal overlaying section to overlay a video signal output of said second video signal decoding section at a predetermined position on a video signal output of said first video signal decoding section and to output the overlaid signal;
wherein said second video signal decoding section has:
a variable-length decoder which (1) variable-length decodes said video signal compressed stream and (2) extracts a motion vector, a quantization step which is a divisor employed in quantization, and Mxc3x97N DCT coefficients consisting of M coefficients in a horizontal direction (where M is a natural number from 1 to 8) and N coefficients in a vertical direction (where N is a natural number from 1 to 8);
an inverse quantizer to quantize said Mxc3x97N DCT coefficients inversely;
memory to store the decoded video signal;
a motion compensator to compensate motion by employing both a video signal compensated and decoded after said motion vector has been transformed in horizontal and vertical directions by a predetermined transformation and a video signal stored in said memory; and
a memory controller to control writing of data to said memory and reading of data from said memory.
With this, for example, a broadcasting program on a different channel can be readily displayed on a small screen within a main screen when a digital broadcast is received.
The fortieth invention of the present invention is a digital broadcasting signal storing method of receiving and storing a broadcasting signal compressed by the Moving Picture Experts Group (MPEG) standard and multiplexed, comprising the steps of:
receiving said broadcasting signal and performing a predetermined demodulation;
separating a video signal compressed stream from the demodulated broadcasting signal;
decoding the separated video signal compressed stream;
based on a predetermined flag in the decoded stream, and/or based on a predetermined motion vector and predetermined DCT coefficients in the decoded stream, (1) converting various formats in said decoded stream to a predetermined format, and/or (2) reducing the data amount of said decoded stream, and then (3) encoding said decoded stream; and
storing the encoded stream in a predetermined storage medium.
The forty-first invention of the present invention is a digital broadcasting signal storage for storing a broadcast compressed by the Moving Picture Experts Group (MPEG) standard, comprising:
a demodulating section to perform a predetermined demodulation on a digital broadcast which is broadcasted by compressing a video signal and an audio signal by the MPEG standard and performing predetermined multiplexing and modulation on the video and audio signals;
a separating section to separate video and audio signal compressed streams on a predetermined channel by releasing said predetermined multiplexing;
memory to store the separated audio signal compressed stream temporarily;
a variable-length decoder to perform variable-length decoding on the separated video signal compressed stream and to select various flags, motion vectors, and a predetermined number of DCT coefficients (M coefficients in a horizontal direction where M is a natural number from 1 to 8 and N coefficients in a vertical direction where N is a natural number from 1 to 8);
a variable-length encoder to perform variable-length encoding on the selected various flags and motion vectors, by performing a predetermined flag transformation on the selected various flags and also performing a motion vector transformation on the selected motion vectors;
a multiplexing section to multiplex the variable-length encoded video signal data and said audio signal compressed stream; and
a storage section to store the multiplexed data in a predetermined storage medium.
With this, for example, either by thinning out DCT coefficients to reduce the quantity of data to be stored or to slow down the storing speed of requisite data, or by encoding DCT coefficients again, even in the case where video signals in various formats (resolution, frame frequency, etc.) are input, the video signals can be stored in a storage medium as a signal format.
The forty-second invention of the present invention is a digital broadcasting signal storage for storing a broadcast compressed by the Moving Picture Experts Group (MPEG) standard, comprising:
a demodulating section to perform a predetermined demodulation on a digital broadcast which is broadcasted by compressing a video signal and an audio signal by the MPEG standard and performing predetermined multiplexing and modulation on the video and audio signals;
a separating section to separate video and audio signal compressed streams on a predetermined channel by releasing said predetermined multiplexing;
memory to store the separated audio signal compressed stream temporarily;
a variable-length decoder which variable-length decodes the separated video signal compressed stream and selects various flags, (1) performs a motion vector transformation when a motion vector has been determined in a frame unit, (2) converts the motion vector to a frame unit by a predetermined approximation method when the motion vector has been determined in a field unit, (3) selects only a predetermined number of DCT coefficients (M coefficients in a horizontal direction and N coefficients in a vertical direction where M and N are a natural number from 1 to 8) when DCT coefficients have been determined in a frame unit, and (4) deletes one group of DCT coefficients and selects only a predetermined number of DCT coefficients (M coefficients in a horizontal direction and K coefficients in a vertical direction where M and K are a natural number from 1 to 8) when DCT coefficients have been determined in a field unit;
a variable-length encoder to perform variable-length encoding on the selected various flags, motion vectors, and DCT coefficients by performing a predetermined flag transformation on the selected various flags, motion vectors, and DCT coefficients;
a multiplexing section to multiplex the variable-length encoded video signal data and said audio signal compressed stream; and
a storage section to store the multiplexed data in a predetermined storage medium.
With this, for example, either by thinning out DCT coefficients to reduce the quantity of data to be stored or to slow down the storing speed of requisite data, or by encoding DCT coefficients again, even in the case where video signals in various formats (resolution, frame frequency, etc.) are input, the video signals can be stored in a storage medium as a single format.
The forty-third invention of the present invention is an apparatus for reproducing a video signal and an audio signal, comprising:
a reproducing section to reproduce data stored in the digital broadcasting signal storage as set forth in said forty-first or said forty-second invention;
a separating section to separate the reproduced data into video and audio signal compressed streams;
a video signal decoding section to decode the separated video signal compressed stream; and
an audio signal decoding section to decode the separated audio signal compressed stream;
wherein the video signal decoding section has:
a variable-length decoder to perform variable-length decoding on said video signal compressed stream;
an inverse quantizer to quantize the variable-length decoded data inversely;
an IDCT unit to perform an inverse Mxc3x97N or Mxc3x97K DCT (where M, N, and K are a natural number from 1 to 8) on the inversely quantized data;
memory to store the decoded video signal;
a motion compensator to compensate motion by employing both a video signal decoded with a motion vector and a video signal stored in said memory; and
a memory controller to control writing of data to said memory and reading of data from said memory.
With this, for example, by thinning out DCT coefficients, the quantity of data to be stored can be reduced and the speed of requisite data can be slowed down.
The forty-fourth invention of the present invention is a digital broadcasting signal storage for storing a broadcast compressed by the Moving Picture Experts Group (MPEG) standard, comprising:
a demodulating section to perform a predetermined demodulation on a digital broadcast which is broadcasted by compressing a video signal and an audio signal by the MPEG standard and performing predetermined multiplexing and modulation on the video and audio signals;
a separating section to separate video and audio signal compressed streams on a predetermined channel by releasing said predetermined multiplexing;
memory to store the separated audio signal compressed stream temporarily;
a video signal decoding section to decode the separated video signal compressed stream;
a video signal compression section to compress a video signal which is the output of said video signal decoding section;
a multiplexing section to multiplex the video signal compressed stream compressed at said video signal compression section and said audio signal compressed stream; and
a storage section to store the multiplexed data in a predetermined storage medium;
wherein said video signal decoding section has:
a variable-length decoder to perform variable-length decoding on said video signal compressed stream;
an inverse quantizer to quantize the variable-length decoded data inversely;
an IDCT unit to perform an inverse DCT on the inversely quantized data;
memory to store the decoded video signal;
a motion compensator to compensate motion by employing both a video signal decoded with a motion vector and a video signal stored in said memory; and
a memory controller to control writing of data to said memory and reading of data from said memory; and
wherein said video signal compression section has:
a filtering unit to change resolution of a video signal by performing a predetermined filtering operation on a reproduced video signal of a video signal compressed stream during a digital broadcast, the reproduced video signal being the output of the video signal decoding section;
a differential signal generator to generate a differential signal of the filtered reproduced video signal by employing said motion vector present in said video signal compressed stream which is the output of said video signal compressed stream which is the output of said video signal decoding section;
a DCT unit to perform DCT on the differential signal;
a quantizer to quantize data after DCT by employing said various flags which are input to the quantizer; a variable-length encoder to variable-length encode the output of said quantizer; and said video signal compression section outputs a new video signal compressed stream.
With this, for example, either by thinning out DCT coefficients to reduce the quantity of data to be stored or to slow down the storing speed of requisite data, or by encoding DCT coefficients again, even in the case where video signals in various formats (resolution, frame frequency, etc.) are input, the video signals can be stored in a storage medium as a single format.